Agricultural combines separate crop plants from the field, then separate the crop plants into a crop portion and a residue portion. The crop portion is saved within the agricultural combine for later transfer to storage facilities, and the residue portion is distributed over the ground.
Crop residue is typically chopped into short pieces before it is distributed over the ground. This chopping is performed by residue choppers that are typically constructed as a drum from which short blades are suspended. As this drum rotates the blades extending from the drum hit the stalks of the crop plant and cut them against a row of stationary blades.
Once the crop is chopped, it is thrown out the rear of the combine and is spread over the ground. Typically, a row of steering vanes are provided behind the chopper to spread the chopped plant stalks to the left and to the right of the combine.
One problem with this arrangement is the velocity of the chopped crop plants. They must have a relatively high velocity to be chopped, bounced against steering vanes, and continue onward 5-10 m to the left and to the right of the combine.
One way to improve the velocity of the chopped up plant stalks is to operate the chopper at a high rate of speed, such as 3000 RPM. Another way is to add fan blades to the chopper that will increase the air flow through the chopper, and thus blow the chopped crop plants farther away from the vehicle.
When these solutions are adopted, the chopper consumes significantly more power. Further, since it is the chopper that provides the impetus to the chopped crop plants, the chopper speed cannot be varied to control the quality of the chopping, but must operate at a very high speed in order to ensure the chopped crop plants are widely distributed.
What is needed, therefore, is a system of chopping and spreading residue that permits the chopper to operate more efficiently, and to chop more effectively, yet provide a wide distribution of chopped crop plants behind the combine. It is an object of this invention to provide such a system.